The invention generally relates to photovoltaic devices and methods of making photovoltaic devices. More particularly, the invention relates to photovoltaic devices that include an absorber layer and methods of making photovoltaic devices that include an absorber layer.
Thin film solar cells or photovoltaic devices typically include a plurality of semiconductor layers disposed on a transparent substrate, wherein one layer serves as a window layer and a second layer serves as an absorber layer. The window layer allows the penetration of solar radiation to the absorber layer, where the optical energy is converted to usable electrical energy. Cadmium telluride/cadmium sulfide (CdTe/CdS) heterojunction-based photovoltaic cells are one such example of thin film solar cells. Cadmium telluride (CdTe)-based photovoltaic devices typically demonstrate relatively low power conversion efficiencies, which may be attributed to a relatively low open circuit voltage (Voc) in relation to the band gap of the material, which is due, in part, to the low effective carrier concentration and short minority carrier lifetime in CdTe.
Improving minority carrier lifetimes in the absorber material may be desirable. Further, improved methods of depositing the CdTe layer on the CdS layer resulting in improved performance may be desirable.